This proposal seeks funding to develop a long-term research program on Sundaland, focusing on the two of the largest rivers in their discharge in Southeast Asia: Chao Phraya in Thailand and Mekong in Cambodia. These two rivers are the main natural resources for the nations (e.g. energy production, irrigation sources, food supply, recreation, and transportation), and thus the majority of the population and Gross Domestic Products (GDP) are concentrated along these rivers.

The systems are also hotspots of biodiversity. The rivers’ hydrological and sedimentological regimes, however, are largely vulnerable to natural hazards such as tropical cyclones, recurrent floods, and frequent landslides. For that reason, Chao Phraya and Mekong are considered two of the riskiest and the most vulnerable rivers to natural disasters in the world.

These rivers also have been intensively affected by human activities recently, due to the rapid growth in population and economic developments (e.g. mining, deforestation, dam constructions, etc.). Human modifications of the hydrological regimes, sediment inputs, and floodplain storage have triggered strong impacts on riverine landscapes including delta and estuarine environments that depend on organic and inorganic fluxes from the rivers.

For example, reduction of sediment supply reduces the area of the deltas, and this is considered one of the most significant geological changes in the world affecting habitability. It has been recently reported that deltas around Sundaland (mainly the Mekong) are facing the most serious challenges on the planet, combined with the rising sea levels and poor governance. However, even until now, there is no systematic investigation of the river basins’ environmental vulnerability to recurrent natural disasters and ever-increasing human impacts. There are only a few case studies on these two rivers, and environmental vulnerability of these basins. As such, knowledge on river dynamics, sediment transport and floods is still nascent.